Using OpenZac with AI

Install the OpenZac CLI to give your AI assistant direct access to sales tax allocation data. Works with Claude Code, Codex CLI, Gemini CLI, and more.

#Installation

Requires Node.js >= 20.

npm install -g @zactax/openzac

To update to the latest version:

npm update -g @zactax/openzac

#Authentication

Sign up for a free API key at open.zactax.com, then log in:

openzac login

You'll be prompted to enter your API key via masked input. On macOS, your key is stored securely in the system keychain. On other platforms, it's stored at ~/.config/openzac/settings.json with restricted permissions.

To remove your stored API key:

openzac logout

#Setting Up AI Agents

OpenZac ships as an MCP server, so AI coding agents can query tax data on your behalf.

#Supported agents

#Automatic setup

Run the interactive setup wizard to configure MCP for any detected agent:

openzac agents

#Manual setup

If you prefer to configure things manually, here are the instructions for each agent.

Claude Code:

claude mcp add --scope user openzac -- openzac mcp

Claude Desktop — add to your claude_desktop_config.json:

{
  "mcpServers": {
    "openzac": {
      "command": "openzac",
      "args": ["mcp"]
    }
  }
}

Codex CLI — add to ~/.codex/config.toml:

[mcp_servers.openzac]
command = "openzac"
args = ["mcp"]

Gemini CLI — add to ~/.gemini/settings.json:

{
  "mcpServers": {
    "openzac": {
      "command": "openzac",
      "args": ["mcp"]
    }
  }
}

#Uninstall from all agents

openzac agents uninstall

#Example

Once configured, you can ask questions of OpenZac data directly in the AI system of your choosing. For example, asking Claude Desktop: "How did Austin, Texas' sales tax perform in 2025?" should generate:

• A call to the query_jurisdictions tool, searching for "Austin" in state "tx" in order to fetch the OpenZac ID for that city
• A call to the query_texas_sales_tax tool to fetch the relevant sales tax allocation data

With the data in hand, Claude will be able to summarize and answer your question.

NOTE: As with any AI system, please double check anything you see. Our MCP server helps to ground the AI platform with a source of truth, but that doesn't mean it's always going to be 100% accurate.

#CLI Usage

The OpenZac CLI can also be used directly from the command line.

For full CLI usage and command reference, see the package documentation on npm.